The DUB will likely arrive into T5A. The BLR flight would be T5B or T5C.
You can go to T5B and T5C, but you need to be careful when coming back to T5A. If you take the train, then you'll end up at arrivals, and have to clear security again. That may cause issues as you've already been processed once.
If you walk, then there are no issues.